Rule Definition
A primary key value must never change after it's first assigned. Since it is a generated key, it is automatically set by Hibernate, another JPA implementation or by other provider. The actual behavior when an application tries to modify the value of a primary key is not defined.

Remediation
Set the setter method as private.

Violation Code Sample

------> sample.hbm.xml:
...
<class name="Sample" table="SAMPLE">
           <id name="id" column="id" type="long">
                  <generator class="sequence"/>
           </id>
           ...
</class>

------> Sample.java:
public class Sample {
   private long id;
...

  public void setId(long id) { // VIOLATION
     this.id = id;
  }

   public Long getId() {
      return id;
   }
}

Fixed Code Sample

------> Sample.java:
public class Sample {
   private long id;
...

  private void setId(long id) { // FIXED
     this.id = id;
  }

   public Long getId() {
      return id;
   }
}

Hibernate in Action (ISBN 1932394-15-X) p 89 Java Persistence with Hibernate (ISBN 1-932394-88-5) p 163 The Java Persistence API ( ISBN 1-932394-88-5) p 163, 416 http://docs.jboss.org/hibernate/core/3.3/reference/en/html/tutorial.html#tutorial-firstapp-firstclass http://burtbeckwith.com/blog/?p=53